134 THE ROYAL SOCIETY OF CANADA 



alin — makes reductase comparable with the ferment in the laurel leaf 

 studied by Dr. Waller.-^ Chloroform was found to kill the leaf, but to 

 set free an enzyme which liberated HCN. 



6. As a ferment, reductase is rather easily inactivated by drying the 

 juice in vacuo at lô°C, and by precipitation from juice by absolute 

 alcohol. As might be expected, chying and alcohol injure it less in 

 tissues than in press-juice. 



It clings with considerable tenacity to the cell-proteins which 

 evidently guard it from inactivation by heat, by drying and by alcohol. 



In regard to its sensitiveness towards alcohol, reductase is in 

 marked contrast with glycogenase which can be obtained in an active 

 state even from livers which have been for months under alcohol. This 

 power that colloids have of protecting enzj^mes is a well known property 

 of the interaction between these two classes of bodies. 



As judged by the criterion of solubility, reductase is comparatively 

 insoluble; it will not, for instance, dialyse away from the cell-proteins. 

 But in that it can in some measure pass into solution in dilute glycerol, 

 it cannot be regarded as entirely of an insoluble nature 



The insoluble endo-enzyme is now fully recognised. Professor 

 Adrian Brown tells me that phyto-enzymes of a non-soluble order exist; 

 and according to Vernon- the oxidase of the liver is insoluble. He adds 

 that its insolubility does not preclude its enzymic nature, as there 

 is a good deal of evidence pointing to a similar property in some 

 lipolytic enzymes. 



VIII. Remarks on Tissue Respiratory Ferments. 



Besides deductase, at least two other types of enzyme exist in the 

 liver, to confine our attention only to the liver in the meantime, namely 

 a catalase and an oxidase or a number of oxidases. A catalase has long 

 been recognised in the blood and tissues; Creighton and I-^ recently 

 wrote : — 



"The existence of a catalytic enzyme in the mammalian liver is 

 fully confirmed. The decomposition of HjOj is effected by this enzyme, 

 and is not due to the presence of proteins or other organic matter in 

 the press-juice. " 



Boiled juice gives rise to no decomposition of HjOj; and the amount 

 of HjOj decomposed bears no relation at all to the amount of protein in 

 the juice, for a few drops of a very dilute juice reduced 97-2% of HjOj 

 in the first five minutes. No doubt it is possible that the two enzymes, 

 catalase and reductase, may co-operate in hepatic reductions. 



The presence of an oxidase, more probably of oxidases, must be 

 remembered when one is working with the reducing ferment. As Dr. 



